"Error importing data: java.lang.NullPointerException" when importing in JIRA

2011-12-05 14:31:05,258 JiraImportTaskExecutionThread-1 INFO superadmin 848x1092x2 b654b 10.62.65.6 /secure/admin/XmlRestore.jspa [jira.bc.dataimport.DefaultDataImportService] Importing data is 90% complete...
2011-12-05 14:31:21,148 JiraImportTaskExecutionThread-1 INFO superadmin 848x1092x2 b654b 10.62.65.6 /secure/admin/XmlRestore.jspa [jira.bc.dataimport.DefaultDataImportService] Finished storing Generic Values.
2011-12-05 14:31:22,679 JiraImportTaskExecutionThread-1 ERROR superadmin 848x1092x2 b654b 10.62.65.6 /secure/admin/XmlRestore.jspa [jira.bc.dataimport.DefaultDataImportService] Error importing data: java.lang.NullPointerException
java.lang.NullPointerException
	at com.atlassian.activeobjects.backup.ActiveObjectsForeignKeyCreator.create(ActiveObjectsForeignKeyCreator.java:51)
	at com.atlassian.activeobjects.backup.ForeignKeyAroundImporter.after(ForeignKeyAroundImporter.java:29)
	at com.atlassian.dbexporter.importer.AbstractImporter.importNode(AbstractImporter.java:53)
	at com.atlassian.dbexporter.DbImporter.importData(DbImporter.java:73)
	at com.atlassian.activeobjects.backup.ActiveObjectsBackup.restore(ActiveObjectsBackup.java:155)
	at com.atlassian.jira.bc.dataimport.DefaultDataImportService.restoreActiveObjects(DefaultDataImportService.java:347)
	at com.atlassian.jira.bc.dataimport.DefaultDataImportService.performImport(DefaultDataImportService.java:479)
	at com.atlassian.jira.bc.dataimport.DefaultDataImportService.doImport(DefaultDataImportService.java:209)
	at com.atlassian.jira.web.action.setup.DataImportAsyncCommand.call(DataImportAsyncCommand.java:65)
	at com.atlassian.jira.web.action.setup.DataImportAsyncCommand.call(DataImportAsyncCommand.java:28)
	at com.atlassian.jira.task.ImportTaskManagerImpl$TaskCallableDecorator.call(ImportTaskManagerImpl.java:147)
	at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
	at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at com.atlassian.multitenant.impl.DefaultMultiTenantManager.runForTenant(DefaultMultiTenantManager.java:61)
	at com.atlassian.multitenant.juc.MultiTenantExecutors$WrappedRunnable.run(MultiTenantExecutors.java:160)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
2011-12-05 14:31:22,679 JiraImportTaskExecutionThread-1 INFO superadmin 848x1092x2 b654b 10.62.65.6 /secure/admin/XmlRestore.jspa [jira.bc.dataimport.DefaultDataImportService] Importing data is 100% complete...
2011-12-05 14:31:22,679 JiraImportTaskExecutionThread-1 INFO superadmin 848x1092x2 b654b 10.62.65.6 /secure/admin/XmlRestore.jspa [jira.bc.dataimport.DefaultDataImportService] JIRA Data Import has finished.